Government regulation relating to spectrum use takes into account many priorities and objectives, balancing commercial interests with critical infrastructure or national security needs, examples of which include military radar, navigational radio beacons, and radio-location installations. To protect the frequency bands used for critical infrastructure and security purposes, spectrum use restrictions have been established to ensure that authorized devices and protected services associated with those devices are not disrupted. Governments also restrict use of radio-frequency devices in parts of their territory immediately adjacent to borders they share with other authorities, since roaming radio-frequency terminals may stray arbitrarily close to a border area, and from this location may transmit radio-frequency signals across the border which interfere with communications within the domain of, and under the control of another authority.
The ever expanding use of wireless communications is demanding more intensive utilization of RF spectrum resources in border areas, and within frequency bands where pre-existing protected radio-frequency installations have typically enjoyed exclusive use. Restricting all commercial communications in restricted frequency bands in many cases is inefficient and unnecessary since only transmissions within a certain geographic range and above a certain power threshold would threaten the authorized devices and the protected services.